Optical Coherence Tomography (OCT) is a non-invasive optical imaging technique which produces depth-resolved reflectance imaging of samples through the use of a low coherence interferometer system. OCT imaging allows for three-dimensional (3D) visualization of structures in a variety of biological systems and non-biological systems not easily accessible through other imaging techniques. In some instances OCT may provide a non-invasive, non-contact means of assessing information without disturbing or injuring a target or sample. In medicine for example, OCT applications have included but are not limited to non-invasive means of diagnosis of diseases in the retina of the eye, interventional cardiology treatment and assessment, and diagnostics of skins lesion for dermatology.
Generally, OCT is used to generate 3D images of various structures, including vessels such as blood vasculature. Previously described methods of OCT provide methods for obtaining structural information directed at acquiring information about the size, shape, topology and physical attributes of the outside structures of vessels. However, information regarding physical and chemical attributes inside vessels and structures can also be useful, yielding more functional and potentially useful information about a system.
In medical diagnostics for example, vascular visualization and quantitative information about attributes of blood can be important for the diagnosis and treatment of many diseases. For example, approximately 50% of Americans will get cancer and approximately 50% of those will die from cancer. In the example of ocular disease, such as diabetic retinopathy, age related macular degeneration (AMD), glaucoma, nearly 10 million people in the U.S. and over 200 million people worldwide may be at risk for vision loss or blindness. It is suspected that vasculature remodeling and biochemical pathways that affect abnormal morphology of blood supplies in the eye and around tumors may be correlated with the onset and prognosis of these diseases, respectively. In some examples, an abnormal increase or decrease in metabolism, illustrated through abnormal blood vessel proliferation may also correlate with disease.
Non-invasive methods that allow acquisition of information about tissue attributes related to the etiologies of diseases, may lead to prevention of such diseases. The ability to measure blood flow, and other various biochemical analytes within a blood flow, such as oxygen (pO2), glucose or other biomarkers can help indicate a functional state of target tissue, such as metabolic activity. In some examples, the ability to understand a functional state of a target tissue, can be useful for treatment, monitoring or prevention of disease. This especially true when attributes such both as blood flow and oxygen can both be measured. Currently, there are no non-invasive three dimensional (3D) imaging techniques to measure oxygen metabolism in vivo in tissues. There is need in the art for improved methods and devices for non-invasive 3D quantitative imaging of metabolism and other target functions for a variety of applications including but not limited to the treatment and diagnosis of disease.